This study proposes a further investigation of the pattern of neural connectivity of the ascending projections of the primate visual system. Specifically, we propose to examine the connections of three sets of nuclei, each of which terminates densely within visual cortex with the goal of providing an anatomical base from which we may address questions concerning: 1) the function of the lamination of the lateral geniculate nucleus, 2) the relationship between the tree shrew lateral intermediate nucleus and visual cortex, 3) the functional significance of the claustrum. Of particular importance is whether particular geniculate layers provide distinct channel to striate cortex for non-retinal afferents in all primates. Our preliminary evidence suggests that the answer is yes, and that on particular channel, the small-cell geniculate layers, may provide a second path for tectal input to cortex. Objectives of other studies will be to determine if the pattern of connectivity of the lateral intermediate nucleus of the tree shrew warrants the speculation that this nucleus represents the homologue of parts of the pulvinar nucleus of other primates. Further, we will examine the afferent and efferent projections of the tree shrew claustrum with the objective of determining if the pattern of projections with cortical, as well as subcortical areas will provide clues as to what neural projections it provides. Finally, since each of these ascending nuclei have projections that terminate in multiple cortical layers, the results will allow an assessment of whether particular similarities exist for neural regions terminating in one cortical layer that do not exist for neural regions terminating in other cortical layers.